Twenty years into her marriage, Kat and her husband faced head-on the
great underlying fear of most monogamous people: My partner wants to
have sex with other people. For them, that truth led to a rollercoaster
of new sexual and romantic adventures...

Sometimes a relationship doesn't work the way you think it will. Sometimes you go into something expecting it to look and feel a certain way, travel a certain path, and as you go, it turns out that is not what you (or the other person(s)) wanted after all.